Corrosion inhibitors and compositions containing the same



CORROSION HBITORS AND COMPOSITIONS CONTAMING THE SAME N Drawing.Application February 20, 1953, Serial No. 338,163

16 Claims. (Cl. 252-32.7)

This invention relates to improved compositions which are effectivecorrosion inhibitors and which are noncorrosive to silver, silver alloysand similar metals. More particularly, the invention pertains tolubricant compositions which are non-corrosive to such metals andinhibit the corrosion thereof by sulfur and/ or corrosivesulfur-containing compounds.

Advances in the design and construction of internal combustion enginesaimed at increased efliciency and economy have led to lubricationproblems. To meet the increased severe demands upon engines, many typesof lubricant additives have been developed to obtain certain desiredcharacteristics. Among the more effective addition agents which havebeen developed for compounding with lubricants are manysulfur-containing organic compounds, such as sulfurized terpenes,sulfurized hydrocarbon oils, vegetable oils or animal oils, xanthateesters, organic polysulfide, particularly polyalkyl polysulfides, metalsalts of organo-substituted thioacids of phosphorus, metal salts of thereaction product of a phosphorus sulfide and a hydrocarbon, such as forexample, polybutenes and other polyolefins, and combinations of theforegoing.

Recent increased use of silver and similar metals in the construction ofimproved internal combustion engines has created new problems in the useof sulfur-containing additives in lubricants for such engines; theprimary problem created being the corrosion of such silver parts of theengine by the sulfur-containing additives. While such corrosion can beeliminated by avoiding the use of sulfurcontaining additives inlubricants for such engines, this solution of the problem is accompaniedby the loss of the highly desired beneficial effects of the additives ofthis type.

It is an object of the present invention to provide a non-corrosivecomposition. Another object of the invention is to provide a compositionnon-corrosive to silver and similar metals. A further object of theinvention is to provide a composition which will inhibit the corrosionof silver and similar metals by sulfur and/or organic sulfur-containingcompounds. A still further object of the invention is to provide alubricant composition which is non-corrosive. Still another object ofthe invention is to provide a lubricant composition containing anaddition agent which will inhibit the corrosion of silver and similarmetals by sulfur and/ or organic sulfur-containing compounds. A furtherobject of the invention is to provide a method of inhibiting thecorrosion of silver and similar metals, Still another object of theinvention is to provide a method of lubricating internal combustionengines containing silver and similar metal parts, and inhibiting thecorrosion of such metals by lubricants which contain sulfur and/ororganic sulfur-containing compounds.

In accordance with the present invention the foregoing objects can beattained by employing in oleaginous mate- Patented July 16, 1957 'ice inwhich R is a hydrocarbon radical and x is an integer at least 1 and canbe as high as 9; preferably x is an integer l to about 7. Thehydrocarbon radical R can be aliphatic or aromatic, including acylic,alicyclic, aralkyl, aryl, alkaryl, and alkyl radicals. The hydrocarbonradical can contain from 2 to about 30 carbon atoms, and preferably fromabout 8 to about 20 carbon atoms. Examples of suitable hydrocarbonradicals are ethyl, butyl, hexyl, octyl, nonyl, decyl, dodecyl,hexadecyl, octadecyl, cyclo-hexyl, phenyl, tolyl, benzyl, styryl,terpene radicals, etc.

Compounds of the above general formulation can be prepared by severalmethods. For example, they can be prepared by reacting2-mercapto-4-phenyl-S-thione-1,3,4- thiadiazole with an olefiniccompound, or by chlorinating the thiadiazole and subsequently reactingthe chlorinated thiadiazole with a mercaptan. The thiadiazole can alsobe reacted with a sulfenyl halide (RSX); this reaction product per secan be used, or it may be further reacted with sulfur.

The preparation of compounds of the above general formulation isillustrated by the following examples:

EXAMPLE 1 A mixture of 22.6 parts of 2-1nercapto-4-phenyl-S-thione-1,3,4-thiadiazole and 20 parts of dipentene was stirred andheated at l00-110 C. for 2 hours. The excess dipentene was distilled invacuum, and the bottoms filtered to give an oil-soluble brown viscousoil having a sulfur content of 29.3% and a nitrogen content of 8.32%.

EXAMPLE 2 The procedure of Example 1 was followed, substituting 16 partsalpha-methyl styrene for the dipentene. An oilsoluble dark brown viscousoil having a sulfur content of 25.2% and a nitrogen content of 7.95% wasobtained.

EXAMPLE 3 The procedure of Example 1 was followed, substituting 20 partsof pinene for the dipentene. An oil-soluble viscous oil having a sulfurcontent of 21.3% and a nitrogen content of 6.82% was obtained.

The reaction products of the above examples have the general formulaEXAMPLE 4 small amount of light yellow crystals having a melting pointof 86 C.

EXAMPLE 1,3,4-thiadiazole (0.185 mole) and the reaction mixture warmedto C. 'and'stirred for4 hours. The reaction mixture waswashed withdilute alkali and water, and then stripped at 110 C. With nitrogen toremove oil-soluble clear brown liquid and 5.93% nitrogen.

The theoretical for is 30.1% sulfur and 6.5 7% nitrogen.

'EjQAh/IPLE 6 i Portions of the reaction product of Example 5 were Iheated with sufficient sulfur at .1309 C. for III/2317161118 to give thefollowing polyalkyl sulfides of 4-phenyl-'5-' I Ithioh'e-l,3,4thiadiazole:'

ence'of' a catalyst, such: as sulfuric acid, phosphoric acid, boronfluoride, aluminum chloride,'or other similar halide catalysts of theFriedel-Crafts type.

The polymers employed, are preferably mono-olefin polymers ormixtures-of mono-olefin polymers and isomono-olefin polymers havingmolecular Weights ranging from about .150 to 50,000 or more, andpreferably from carbon tetrachloride- The recovered product was ancontaining 28.5% sulfur thesepolymers, a hydrocarbon'mixture containingiso-' butylcne,'butylenes and butanes recovered frompetroabout 500 toabout 10,000. Suchpolymerscan beobtained, for example, by thepolymerization in the liquid phase of a hydrocarbon mixture containingmonoand isomono-olefinnsuch as butylene; and isobutylene at a'temperature of from about -80 to about 100 P, in the presence of ametalhalide catalyst, of the Friedel- Crafts type, such as for example, boronfluoride, aluminum chloride, and the like. In the preparation of leumgases, especially those gases produced in the cracking of petroleum oilsin themanufacture of gasoline, can be used.

Another suitable polymer is that obtained by polymerizing inthe liquidphase, a hydrocarbon mixture,

7 comprising substantially C3 hydrocarbons in the presence (a) 2 lauryltrisulfide 4 phenyl-5-thione-'1,3,4-thiadiazole;

azole; I (c) 2 lauryl hcptasulfide-4wphenyl 5-thionc-1,3,4-thiadiazole.

' The above described reaction products can be used 'in amounts offromabout 0.02% to about 10%, and

preferably from about 0.25% to about 5%, in combination with lubricantbase oils, such as hydrocarbon oils, synthetic hydrocarbon oils, such asthose obtained by the polymerization of hydrocarbons, such as olefinpolymers; synthetic lubricating oils of the alkylene-oxide type, forexample, the Ucon oils, marketed by Carbide and Carbon Corporation, aswell as other synthetic oils, such as the polycarboxylic acid ester-typeoils, such as the esters of adipic acid, sebacic acid, maleic acid,azelaic acid, etc.

While the above-described reaction products can be suitably employedalone in combination with a base oil, they are usually used incombination With other lubricant addition agents, which impart variousdesired characteristics to the base oil. Usually, these reactionproducts are used in conjunction with detergent-type additives,particularly those which contain sulfur or phosphorus and sulfuraddition agents. This type is usually used in amounts of from about0.002% to about 10%, and preferably from about 0.01% to about 5%. Amongthe phosphorus and sulfur-containing addition agents are the neutralizedreaction products of a phosphorus sulfide and a hydrocarbon, an alcohol,a ketone, an amine or an ester. Of the phosphorus sulfide reactionproduct additives, we prefer to employ the neutralized reaction productsof a phosphorus sulfide, such as a phosphorus pentasulfide, and ahydrocarbon of the type described in U. S. 2,316,082, issued to C. M.Loan et 211., April 6, 1952. As taught .in this patent, the preferredhydrocarbon constituent of the reaction is a mono-olefin hydrocarbonpolymer resulting from the polymerization of low molecular weightmono-olefin hydrocarbons, such as propylene, butenes, amylenes orcopolymers thereof; Such polymers may be obtained by the polymerizationof mono-olefins of less than 6 carbon atoms in the pres- .of an aluminumchloride-complex. catalyst.

The catalystis preferably prepared by heating aluminum chlo- I ride withisooctane. The hydrocarbon mixture is in troduccd into the bottom of thereactor and passed up- Ward throughthe' catalyst layer, while'atemperature of from about 50 F. toabout 110: 'F. is maintained in thereactor. The propane and other saturated gases .pass throughthe'catalyst, While the propylene is polymerized under these conditions.The propylene polymer can be fractionated to any desired molecularweight, Prfiferably from about-500 to about 1,000 or higher.

Other suitable polymers arethose obtained by polymerizing a hydrocarbonmixture containing about 10% to about 25% isobutylene'at a temperatureof from about 0 .F. to about R, and preferably 0 'F. to about" 329.1 in,the presence of boron-fluoride. After the polymerization of theisobutylene together with a relatively minor amount of the normalolefins present, the reaction mass is neutralized, washed free of acidicsubstances, and the unreacted hydrocarbons subsequently separated fromthe polymers by distillation. The polymer mixture so obtained, dependingupon the temperature of reaction, varies in consistency from a lightliquid to a viscous oily material and contains polymers having molecularweights ranging from about 100 to about 2,000 or higher. The polymers soobtained may be used as such, or the polymer may be fractionated underreduced pres sure into fractions of increasing molecular Weight andsuitable fractions reacted with the phosphorus sulfide to obtain thedesired reaction products. The bottoms result ing from the fractionationof the polymer, which have Saybolt Universal viscosities at 210 F.ranging from about 50 seconds to about 10,000 seconds, are Well suitedfor this purpose.

Essentially paraiflnic hydrocarbons, such as bright stock. residuums,lubricating oil distillates, petrolatums, or paraffin Waxes, may beused. There can also be employed the condensation products of any of theforegoing hycliocarbons, usually through first halogenating thehydrocarbons and reacting with aromatic hydrocarbons in the presence ofanhydrous inorganic halides, such as aluminum chloride, zinc chloride,boron fluoride, and the like.

Examples of other high molecular weight olefinic hydrocarbons which canbe employed are cetcnc (C16), c'erotene (Czs), melene (C30), and mixedhigh molecular weight alkenes obtained by cracking petroleum oils.

Other preferred olefins suitable for the preparation of the phosphorussulfide reaction products are olefins having at least 20 carbon atoms inthe molecule of which from about 13 carbon atoms to about 18 carbonatoms, and

preferably at least carbon atoms, are in along chain. Such olefins canbe obtained by the dehydrogenation of alkyl halides, preferably longchain alkyl halides, particularly halogenated parafiin waxes.

As a starting material there can be used the polymer or syntheticlubricating oil obtained by polymerizing unsaturated hydrocarbonsresulting from the vapor phase cracking of paraffin waxes in thepresence of aluminum chloride which is fully described in U. S. Patents1,955,- 260; 1,970,402 and 2,091,398. Still another type of olefinpolymer which may be employed is the polymer resulting from thetreatment of vapor phase cracked gasoline and/ or gasoline fractionswith sulfuric acid or solid adsorbents, such as Fullers earth, wherebyunsaturated polymerized hydrocarbons are removed. The reaction productsof the phosphorus sulfide and the polymers resulting from thevoltolization of hydrocarbons as described, for example, in U. S.Patents 2,197,768 and 2,191,787, are also suitable.

Other hydrocarbons that can be reacted with a phosphorus sulfide arearomatic hydrocarbons, such as for example, benzene, naphthalene,toluene, xylene, diphenyl, and the like, or an alkylated aromatichydrocarbon, such as for example, benzene having an alkyl substituenthaving at least four carbon atoms, and preferably at least eight carbonatoms, such as a long chain parafiin wax.

The phosphorus sulfide-hydrocarbon reaction product can be readilyobtained by reacting a phosphorus sulfide, for example, P255 with thehydrocarbon at a temperature of from about 200 F. to about 500 F., andpreferably from about 200 F. to about 400 F., using from about 1% toabout 50%, and preferably from about 5% to about 25% of the phosphorussulfide in the reaction. It is advantageous to maintain a non-oxidizingatmosphere, such as for example, an atmosphere of nitrogen above thereaction mixture. Usually, it is preferable to use an amount of thephosphorus sulfide that will completely react with the hydrocarbon sothat no further purification becomes necessary; however, an excessamount of phosphorus sulfide can be used and separated from the productby filtration or by dilution with a hydrocarbon solvent, such as hexane,filtering and subsequently removing the solvent by suitable means, suchas by distillation. If desired, the reaction product can be furthertreated with steam at an elevated temperature of from about 100 F. toabout 600 F.

The phosphorus sulfide-hydrocarbon reaction product normally shows atitratable acidity which is neutralized by treatment with a basicreagent. The phosphorus sulfidehydrocarbon reaction product, whenneutralized with a basic reagent containing a metal constituent, ischaracterized by the presence or retention of the metal constituent ofthe basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can beobtained by treating the acidic reaction product with a suitable basiccompound, such as hydroxide, carbonate, oxide or sulfide of an alkalineearth metal or an alkali metal, such as for example, potassiumhydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, bariumhydroxide, barium oxide, etc. Other basic reagents can be used, such asfor example, ammonia or an alkyl or aryl-substituted ammonia, such asamines. The neutralization of the phosphorus sulfide-hydrocarbonreaction product is carried out preferably in a non-oxidizing atmosphereby contacting the acidic reaction product either as such or dissolved ina suitable solvent, such as naphtha with a solution of the basic agent.As an alternative method, the reaction product can be treated with solidalkaline compounds, such as KOH, NaOH, NazCOs, KzCOs, CaO, BaO, Ba(OH)2,NazS, and the like, at an elevated temperature of from about 100 F. toabout 600 F. Neutralized reaction products containing a heavy metalconstituent, such as for example, fin, titanium, aluminum, chromium,cobalt, zinc, iron, and the like, can be obtained by reacting a salt ofthe desired heavy 6 metal with the phosphorus sulfide-hydrocarbonreaction product, which has been treated with a basic reagent, such asabove-described.

Other phosphorus sulfide reaction products which can be used are thereaction products of a phosphorus sulfide and a fatty acid ester of thetype described in U. S. 2,399,243; the phosphorus sulfide-degrasreaction products of U. S. 2,413,332; the reaction product of analkylated phenol with the condensation product of P285 and turpentine ofU. S. 2,409,877 and U. S. 2,409,878; the reaction product of aphosphorus sulfide and stearonitrile of U. S. 2,416,807, etc.

The silver corrosion inhibiting property of the abovedescribedthiadiazole compound is demonstrated by the data in Table I, which wereobtained by subjecting mixtures of hydrocarbon oil, a neutralizedreaction product of P255 and a polybutene, and various herein-described1,3,4-thiadiazole derivatives to the following test, hereinafterreferred to as the modified EMD test:

A silver strip 2 cm. x 5.5 cm. with a small hole at one end forsuspension is lightly abraded with No. 0 steel wool, wiped free of anyadhering steel wool, Washed with carbon tetrachloride, air-dried andthen weighed to 0.1 milligram. 300 cc. of the oil to be tested is placedin a 500 cc. lipless glass beaker and the oil is heated to a temperatureof 300 F. (:2" F.) and the silver test strip suspended in the oil sothat the strip is completely immersed therein. The oil in the beaker isstirred by means of a glass stirrer operating at 300 R. P. M. At the endof twenty-four hours, the silver strip is removed and while still hotrinsed thoroughly with carbon tetrachloride and air-dried. Theappearance of the strip is then visually noted and given ratingsaccording to the following scale:

l-Bright 2Stained 3-Grey-black 4Black, smooth 5Black, flake After thevisual inspection the silver strip is immersed in a 10% potassiumcyanide solution at room temperature until the silver surface assumesits original bright or silver appearance. The silver strip is thenwashed successively with distilled water and acetone, air-dried, andweighed.

The following lubricant compositions were subjected to the above test,and the results obtained are tabulated in Table I.

Sample A.-Contro1 (solvent-extracted SAE-30 oil+ 3.3% barium-containingneutralized reaction product of P255 and a polybutene of about 1000molecular weight).

Sample B.A+0.75% product of Example 1.

Sample C.-A+0.75% product of Example 2.

Sample D.--A+0.75% product of Example 3.

Sample E.-A+0.75% product of Example 5.

Sample F.A+0.7S% product of Example 6(b).

Sample G.A+0.5% product of Example 6(c).

Table I Sample No.

able, the ability of 1,3,4-thiadiazole derivatives of this invention toinhibit silver corrosion is demonstrated by the above data.

The effectiveness of the herein-described 1,3,4-thiadiazole derivativesin inhibiting corrosion toward copper and/ or lead-containing metals,such as for example, copper-lead alloys, is demonstrated by the data inTable II, obtained by subjecting the above samples to the followingtest:

A copper-lead test specimen is lightly abraded with steel wool, Washedwith naphtha, dried and weighed to the nearest milligram. The cleanedcopper-lead test specimen is suspended in a steel beaker, cleaned with ahot tri-sodium phosphate solution, rinsed with water, acetone and dried,and 250 grams of the oil to be tested, together with 0.625 gram leadoxide and 50 grams of a 30-35 mesh sand charged to the beaker. Thebeaker is then placed in a bath or heating block and heated to atemperature of 300 F. (:2 F.) while the contents are stirred by means ofa stirrer rotating at 750 R. P. M. The contents of the beaker aremaintained at this temperature for twenty-four hours, after which thecopperlead test specimen is removed, rinsed with naphtha, dried andweighed. The test specimen is then replaced in the beaker and anadditional 0.375 gram of lead oxide added to the test oil. At the end ofan additional twenty-four hours of test operation the test specimen isagain removed, rinsed and dried as before, and weighed. The testspecimen is again placed in the beaker together with an additional 0.250gram of lead oxide and the test continued for another twenty-four hours(seventy-two hours total). At the conclusion of this time, the testspecimen is removed from the beaker, rinsed in naphtha, dried andweighed.

The loss in weight of the test specimen is recorded after each weighing.

This test, known as the Stirring Sand Corrosion Test, is

Since weight losses 200 milligrams in 48 hours and 500 milligrams in 72ours are allowable, the copperlead cornsion inhibiting properties of theherein-described 1,3 .4-thiadiazole derivatives are clearly demonstratedby the above data.

Under certain conditions it is desirable to use in lubricantcompositions elemental sulfur or an organic sulfurcontaining compound ofthe type hereinabove described either alone or in combination with otheradditives. Effective lubricant compositions are obtained by thecombination of the neutralized reaction products of a phosphorus sulfideand a hydrocarbon, as above described, with elemental sulfur, or anorganic sulfur-containing compound, such as sulfurized mineral oils,sulfurized non-drying animal and vegetable oils, sulfurized olefins andolefin polymers, sulfurized sperm oil, etc., as described and claimed inU. S. Reissue 22,464, issued to C. D. Kelso et al. April 4, 1944, orwith sulfurized terpenes, for example, dipentene as described andclaimed in U. S. 2,422,585, issued to T. H. Rogers et al. June 17, 1947.While these compounds impart highly desired characteristics tolubricants, and effectively inhibit the corrosion of copper and/or lead,they are corrosive to silver and of h similar metals. In accordance withthe present invention, however, the incorporation in such lubricantcompositions of small amounts, namely, from about 0.1% to about 10%, andpreferably from about 0.25% to about 5%, of the herein-described1,3,4-thiadiazole derivatives effectively inhibits the corrosiveness ofthe silver corrosive compounds without impairing their other desiredproperties.

Although the invention has been described in connection with the use ofthe herein-described 1,3,4-thiadiazole derivatives in combination withthe one or more secondary additives in lubricant compositions, theinvention is not restricted to such use, since these derivatives findutility when used alone in various lubricant compositions or bydrocarbonoil compositions to impart improved and desired characteristics thereto.Thus, for example, these derivatives may be used alone in hydrocarbonoils of high sulfur crudes to inhibit the corrosion of such oils onsilver or copper and/ or lead-containing metals.

In addition to the aforementioned detergenttype additives and corrosioninhibitors, compositions containing the herein-described derivatives of2,5-dimercapto-l,3,4-thiadiazole can contain other additives, such asanti-oxidants, pour-point depressors, extreme pressure agents, anti-Wearagents, V. I. improvers, etc.

While this invention has been described in connection with the use ofthe herein-described additives and lubricant compositions, their use isnot limited thereto; but the same can be used in products other thanlubricating oils, such as for example, fuel oils, insulating oils,greases, nondrying animal and vegetable oils, waxes, asphalts, and anyfuels for internal combustion engines, particularly where sulfurcorrosion must be combatted.

Concentrates of a suitable oil base containing more than 10% of theherein-described thiadiazole derivatives alone or in combination withmore than 10% of the detergenttype additive and/ or the herein-describedcompounds normally corrosive to silver, can be used for blending withhydrocarbon oils or other oils in the proportions desired for theparticular conditions of use to give a finished product containing from0.02% to 10% of the thiadiazole derivative alone or in combination withfrom 0.001% to about 10% of the detergent-type additive and/or thecompound normally corrosive to silver.

Percentages given herein and in the appended claims are weightpercentages unless otherwise stated.

Although the present invention has been described with reference tospecific preferred embodiments thereof, the invention is not to beconsidered as limited thereto but includes within its scope suchmodifications and variations as come within the spirit of the appendedclaims.

We claim:

1. A lubricant composition comprising a major proportion of anoleaginous compound containing a substance normally corrosive to silverselected from the group consisting of elemental sulfur, asulfur-containing organic compound and mixtures thereof, and from about0.02% to about 10% of a thiadiazole having the general formula in whichR is a hydrocarbon radical having from 2 to about 30 carbon atoms and xis an integer of from 1 to 9.

2. A lubricant composition comprising a major portion of a normallyliquid hydrocarbon containing a substance selected from the groupconsisting of elemental sulfur, a sulfur-containing organic compound andmixtures thereof and from about 0.02% to about 10% of a Z-hydrocarbonsulfide-4-phenyl-5-thione-1,3,4-thiadiazole.

3. A lubricant composition comprising a major portion of a hydrocarbonlubricating oil, from about 0.001% to about 10% of a phosphorusandsulfur-containing detergent-type lubricant additive, and from about0.02% to about 10% of a thiadiazole having the general formula in whichR is a hydrocarbon radical having from 2 to about 30 carbon atoms and xis an integer of from 1 to 9.

4. A lubricant composition as described in claim 3 in which R is analiphatic hydrocarbon radical of from about 8 to 20' carbon atoms and xis 1 to 7.

5. A lubricant composition as described in claim 3 in which thethiadiazole is 2-dodecyl disulfide-4-phenyl-5- thione-1,3,4-thiadiazole.

6. A lubricant composition as described in claim 3 in which thethiadiazole is 2-dodecyl heXasulfide-4-phenyl-5-thione-l,3,4-thiadiazole.

7. A lubricant composition as described in claim 3 in which thethiadiazole is Z-tertiary octyl disulfide-4-phenyl-S-thione-1,3,4-thiadiazole.

8. A lubricant composition as described in claim 3 in which thethiadiazole is 2-pinenyl su1fide-4-phenyl-5-thione-1,3,4-thiadiazole.

9. A lubricant composition as described in claim 3 in which thedetergent-type additive is a neutralized reaction product of aphosphorus sulfide and a hydrocarbon.

10. A lubricant composition as described in claim 3 in which thedetergent-type additive is an alkali metal containing neutralizedreaction product of a phosphorus sulfide and an olefin polymer.

11. A lubricant composition as described in claim 3 in which thedetergent-type additive is an alkaline earth metal-containingneutralized reaction product of a phosphorus sulfide and a butylenepolymer.

12. A lubricant composition as described in claim 3 in which thedetergent-type additive is a barium-containing neutralized actionproduct of a phosphorus sulfide and a butylene polymer.

13. A lubricant composition comprising a major proportion of anoleaginous compound, from about 0.001% to about 10% of a compoundnormally corrosive to silver selected from the group consisting ofelemental sulfur, 4

10 in which R is a hydrocarbon radical having from 2 to about 30 carbonatoms and x is an integer of from 1 to 9. 14. A composition as describedin claim 13 in which the sulfur-containing compound is a sulfurizedterpene. 15. An addition agent for corrosive sulfur-containinglubricating oils, comprising a concentrated solution of a hydrocarbonoil containing more than of a thiadiazole having the general formulaL-(Sh-R in which R is a hydrocarbon radical containing from 2 to about30 carbon atoms and x is an integer of from 1 to 9.

References Cited in the file of this patent UNITED STATES PATENTS2,231,353 Watt Feb. 11, 1941 FOREIGN PATENTS 740,213 Germany Oct. 19,1943 OTHER REFERENCES Chemical Abstract, vol. 14, page 1298 citing Ray,Jr., 5 Chem. Soc. (London), vol 115, pp. 1308-12 (1919).

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF ANOLEAGINOUS COMPOUND CONTAINING A SUBSTANCE NORMALLY CORROSIVE TO SILVERSELECTED FROM THE GROUP CONSISTING OF ELEMENTAL SULFUR, ASULFUR-CONTAINING ORGANIC COMPOUND AND MIXTURES THEREOF, AND FROM ABOUT0.02% TO ABOUT 10% OF A THIADIAZOLE HAVING THE GENERAL FORMULA